Constant current source current design with output of 100A

First of all, it is recommended that you abandon the "the higher the accuracy, the better!" The higher the accuracy, the higher the cost, the higher the accuracy, the higher the technical difficulty, the error of 10% is very easy to do, the error of 1% to do it seriously, the error will have to work hard to do, the error is difficult to do, the accuracy to meet the actual needs for the degree, otherwise it will be limited by manpower and material resources and the goal can not be achieved.

If you want to make a constant current power supply with an output of 100A, you need to confirm two parameters first:

1. Maximum output power, or the highest output voltage.

2. Is it fixed 100A, or adjustable, and how big is the adjustable range.

Let's briefly talk about the idea of design and production:

According to the highest output voltage, and the output is greater than 100A, determine a DC power supply, transformer + rectifier; Or switch inverter, add the output 100A adjustment, control link, use the transformer to use thyristor rectification;

The switching inverter is used to control the pulse width of the input pulse of the inverter transformer.

Then there is a precision voltage reference, and the sampling resistor connected to the 100A output loop should be made of manganese copper with a small temperature coefficient.

The voltage from the sampling resistor is compared to the reference voltage, and the difference is amplified to control the thyristor or inverter pulse width.

The output current iout is equal to VCC R2 (R1+R2) R3

The principle is simple, R1 and R2 divide the voltage of VCC and provide the reference voltage vcc R2 (R1+R2) to the op amp's noninverting input pin

According to the imaginary short principle of the op amp working in the closed-loop state, the voltage of the inverting input pin of the op amp is always equal to the voltage of its inverting input pin vcc r2 (r1+r2), because the other end of r3 is grounded, the voltage difference between its two ends is always equal to vcc r2 (r1+r2), so the current flowing through r3 (and also the current flowing through the load rl) iout is always equal to vcc R2 (R1+R2) divided by the resistance value of R3.

This current should be equal to: V*R2 ((R1+R2)*R3).

1. The reference current converted into the mutual impedance amplifier composed of A1 R1 VN222, 2. The voltage drop generated by the reference current on R2, 3. This is used as a reference voltage, and the second mutual impedance amplifier composed of A2 R3 TP0610 is converted into.

The output of this constant current source is range).

You need 1A of current, just change the 51 ohm current sampling feedback resistor to that

A constant current and constant voltage power supply, by adjusting the voltage regulation and current regulation on the panel, so that the no-load output voltage of the power supply is set at 100V, and the constant current value is adjusted at 1A, how does the power supply automatically change the working state of the power supply with the change of load resistance? Through the above introduction, we can know that when the output current is less than 1A, the power supply is in a constant voltage working state, and strives to keep the output voltage to 100V, and the output current changes with the size of the load, and when the current value tends to be greater than 1A, the power supply is in a constant current working state, and strives to keep the output current at 1A, and the output voltage changes with the size of the load. When the output voltage is 100V, the load resistance is 100 ohms, and the output current is 1A, which is the turning point of the two working states of the power supply, and the power supply can be said to be both constant voltage state and constant current state.

For this reason, we can draw the following conclusions about this specific case:

When the load resistance r l = 100 ohms, which is the turning point of the constant voltage and constant current state (voltage = 100 volts and current = 1 a), this concept is very important.

When r l > 100 ohms, the power supply is at constant voltage (voltage = 100 volts, current <1 amp).

When r l < 100 ohms, the power supply is operating at constant current (voltage < 100 volts, current = 1 amp).

In the constant voltage state, the voltage is stable, the current changes with the change of load resistance, the voltage stabilization control unit works, and the current stabilization control unit rests.

In the constant current state, the current is stable, the voltage changes with the change of load resistance, the current stabilization control unit works, and the voltage stabilization control unit rests.

Constant-current constant-voltage power supply

Constant-current power supply

Regulated Power Supply

In the case of BJT, in order to increase the output resistance, it is necessary to try to reduce the early effect (base width modulation effect), that is, to increase the early voltage as much as possible.

In the case of MOSFETs, in order to increase their output resistance, they need to find ways to reduce the channel length modulation effect and the liner effect. Therefore, it is common to use long-channel MOSFETs instead of short-channel devices.